H Dual Mode Dhw Heating With Heating Water Calorifiers In Series, With Vitosolic 200 - Viessmann Vitosol
100 Technical Manual

4.6 System design 6
Dual mode DHW heating with heating water calorifiers connected in series with Vitosolic 200
(especially suitable for large solar heating systems with 20 to 100 m
DHW loading without solar energy
DHW cylinder 2 is heated by the boiler.
The cylinder thermostat with cylinder
temperature sensor qP switches cylinder
loading pump qQ.
DHW loading with solar energy
Heating water calorifier heating
Solar circuit pump 4 is switched ON, if
solar cell 6 detects solar irradiation
above the set threshold value (solar
circulation bypass).
Circulation pump 4 for heating plate
heat exchanger 1 is switched ON, if a
temperature differential greater than
start−up temperature differential DT
measured between temperature sensor
2 and calorifier 2 temperature sensor 3.
Pump 4 will be switched OFF , if the
actual temperature falls below shutdown
temperature differential DT
off
DHW heating
If the temperature differential between
calorifier 1 temperature sensor qW and
the temperature sensor of DHW cylinder
1 qE is higher than start−up temperature
differential DT6 , circulation pumps qR
on
and qT are started, motorised valve wP is
opened, and DHW is loaded via plate heat
exchanger 2.
Pumps qR and qT are switched OFF , and
valve wP is closed, if the actual
temperature falls below shutdown
temperature differential DT6
off
VITOSOL
If the temperature differential between
temperature sensor 5 and temperature
sensor 3 is greater than start−up
temperature differential DT5
valve 9 is opened and calorifiers 1 and 2
are heated by circulation pump 7 (in
case the start−up temperature differential
is exceeded, pump 7 will be
WT−DT
on
is started; it will be stopped if it falls below
on
shutdown temperature differential
WT−DT ).
off
The volume flow in the calorifier loading
circuit is matched to that of the solar
circuit via line regulating valve 8.
The volume flow of the calorifier
unloading circuit and the DHW
preheating stage are matched by means
of line regulating valves qU and qI.
For high water hardness (>20 ºdH), install
a thermostatic mixing valve qO limiting
the heat exchanger flow temperature to
70 ºC to prevent premature scaling up of
heat exchanger 2.
.
2
absorber area)
, motorised
on
Motorised valves 9 and wP , which are
closed in their zero−volt condition,
prevent faulty circulation when calorifiers
are loading or discharged.
The additional function requirements (see
page 60) are met by circulation pump wQ.
4.6 System design 6
79